Pneumatic drill.



J. L. MITCHELL. PNEUMATIC DRILL. APPLICATION FILED JAN.31,1908.

V Patented Dec. 6, 1910.'

2 SHEETS-SHEET 1 INVENTOR I QC Mac/gm. 1

r Writ/m9 J. L. MITCHELL. PNEUMATIC mum. APPLICATION FILED JAN.31,1 9'08.

' Patented Dec. 6, 1910.

2 SHEETS-SHEET 2-v gmmmu INVENTOR.

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I UNITED STATES PATENT. OFFICE I 1 sonnet; mn. COLOR-A130.- U 7 Specification of Letters Patent.

QToaYZ'uliom 'iif'niny r c it known thatI, Jonas L. MITCHELL,

, a resident of Denver, in, the county of Den-1 -i-erand State of Colorado, have invented a new, and useful Improvement in Pneunmtic Drills; and I do hereby declarethe following to be a full, clear, and exact del'scription thereof. p

My invention relates to valve mechanism whereby the number of parts are reduced to.

a' minimum and at the same time labor and costof-manufacture.

invention comprises the novel features hereinafter set 'forthandcla'imed. g Q In the drawings Figure l is alongitudinal f'section oflasuitableshell creasing-showing tfm'y improved valve mechanism and'arrangemerit of ports ;-Fig. 2. is a like View showing the piston'and the positionof the parts when,

the'piston has completed'its forward stroke;

3 is a longitudinalsection .takenat fright angles to Fig. 1, showing the cut-off valve in its rear position; Fig. 4 is a cross :1- ;..}..-section on th line H, Fig. l, and Fig. 5 shows the re. r end of the back head.

i In the drawings the numera1 2 designates a suitable shell or casing within which is the cylindrical chamber 3 containing the I piston '4: The piston 4 has the ,extension 5 1:3 which is adapted to enter the bore 6 formed -.:-.7by the j. extension piece 7 connected to the l casing 2. A' crimp rin 8-bearsagainst the .end ofthe casing 2 an is contained within .gtheextension piece 7. A crimp 9 is inter-v bsed between the ring 10 and the crimp 8 "soas to. form a close packing joint The chuck 11 is. secured within-the extenslgp Z and isifiapted' tohold'the waliobe struck. by the .ha'mmer5 where the device is to be' employed as a pneumatic hammer or coal 'puncher. The head 12 is secured to the easing 2 by means of the screws 18. The head 12 is of larger diameter than the casing 2 and forms the chamber 14. The whole casing, therefore, maybe said to be divided into chambers 3, 14 and 6. a

The inlet port 16 is formed in-the head 12 and said inlet port communicates with the annular groove 17 \vhich. has the ports 18 leading into the chamber 3. These ports 18 are controlled by the 'cut0IL valve 19 confluid operated hammers,'-drills, coalrat-e ten Dec. 6, 1910.

Application filed January 31, 1908. Serial No. 413, 03.

t ained within the'chamber '14 and adapted to move back andforththerein. This valve 19 has the extension or neck portion 20 which is'adapted' to enter the chamber 3 of so thesh ell or casing 2 and so'act to open and close the ports 18. I Contained Within asuitable seat 21 formed in the shellor casing 2 is the controlling valve 22 which is operated by means of the handle 23. This valve 22 has the port 24 extending longitudinally thereof and is provided with ports 1 2 and 3 adapted to be brought into communication with ports 1", 2 and 3 respectively formed in the shell or casing 2. The port 24 of the valve. 22 communicates with the annular groove. 25 "formed in said valve and said groove con municates with the port 26 leading't'o the chamber 14. Formed within the shell or casing 2 isthe port 27 which'communieates at its rear end with the bypass port 28 formed :in the shell or. casing 2. The port'27 at its front end communicates with the chamber 3-at29.. W i

An exhaust valve 30 is containedwithin the chamber 31 formed to receive it in the shell creasing '2. This valve comprises the piston portions 32 and 33 connected by the stem 34. The piston portion 32 Works in the chamber 35 and the piston portion 33 in the chamber 36. Secured to the piston portion 330i the exhaust valve 30 is the stem 37 Which is adapted to enter the seat 38 formed in the head 39. A spring 40 is interposed between the head 39 and the piston portion 33, said s ring acting as a. differential in a mannerl ully hereinafter set forth. The main eh'haust port 42 communicates with the chamber 3 and communicates with the atmos here through the port 41. A port..43 leads om'the chamber 3 to the'chamber 35 and a port 44 conununicates .with the chamber 36. A port 45 leads from the chamber 36 to 'theatmosphere.

A reliefport 46 leads'from the chamber 14 to the atmosphere. A relief port 47 leads from the bore 6to the atmosphere. With the parts in the position indicated in Fig. l the air entering-the inlet 16 passes by the ports 18 into the chamber B and the air imme diately passes by the pert 43 into the charm 'ber 35 and moves the exhaust valve to the position indicated in Fig. 1, shutting off the main exhaustport 42. The pressure admit 11o ted to the chamber 3 carries forward the piston 4 and said pressure continues to be admitted'fto the'chamber if 3; The piston completes it's forward stroke I liau st 41 to theatmosphere. time the pressure in the chamber 35 passes' I out through the port 43. The piston is re.- v

QT-and by-pass port 28 to the front end of the cylinder or-cliamber 6. As soon as the port 42 it forms a Compression which moves 30 greatly simplifying the construction and reducing the number of parts.

a valve which not only said valve-,tothe position indicated in Fig, '2 to close the ports 18 leading to the chamber under the-expansion of'the air. When the piston in its forward-stroke passes the port 4.4.- the fluid pressure-enters the chamber 36 and acts uponthe piston portion 33 of the exhaust valve. This pressure, together-with the differential pressure furnished by the spring 37-, moves the exhaust valve to the position'shoivn in Fig. 2, opening the main ex- At the same turned by the pressure passing by the port piston on its return stroke passes the exhaust tl1e valve.19 and prevents the piston from striking said valve. v By the above construction I thus provide acts as a cut-off but at the same time 'as an admission valve to control the entrance of the air, therebj What I claim is:

1. The combination of a suitable shell or casing having apiston .cliambei'and inlet and exhaust ports, a piston, an exhaust valve, means for directing'the fluid pressurerect-in fluid against said valve to close said exhaust port as said piston advances, and means for di- 1 end 0 .said va veto open said exhaust when said piston has completed or substantially completed its strok'e- The coinbinatidnfof a suitable shell or casing having a piston chamber. and inlet;

and exhaust ports, a piston, an exhaust ressure against the opposite valve, means fordirecting fluid -pressure against said valve to close said exhaust port as said piston advances, and means for directing flu d pressu're from said chamber against the-opposite end of ,said ;exhaustvalve when said piston has completed or sub stantia-llyconi leted its stroke.

3..Tlie com ination of-asuitable'shelhor casing having a piston chamber and-inlet and exhaust ports, a piston, a double piston exhaust valve, means for directing fluid 1 pressure against onetof the pistons of said valve to close said exhaust port whensaid piston advances, and means for directing fluid from said chamber against theopposite'- r piston of said exhaust valve to open'fsaid ex-' I haust when the piston has completedlorsubstantially completed its stroke.

ii-The combination of'a suitable or. piston chamber and inlet and exhaust ports, a piston, a double piston casing having a exhaust valve, means fordirecting the-fluid pressure against one piston of saidexhaust valve to close said exhaust port as said main piston advances, a spring acting against the opposite piston of said exhaust valve, and;

means for directing fluid pressurejfromisaid chamber against said last named piston of said exhaust valve when said main piston has completed or. substantially'coinpleted its stroke.

- In testimony whereof, I the said J ONiLSL,

MiTcnnLL have hereunto set my hand;

- JONAS L. MITCHELL.

lVitnesses: I

BELLE FAIiiLnY, CHARLES J. MUNZ. 

